The present invention relates to a variable speed pulley assembly. In particular, the present invention relates to a variable speed clutch or variable speed pulley assembly for use in a lawn tractor or garden tractor to vary the drive speed of the tractor while the engine speed remains constant.
Summary of the Invention
The present invention is a variable speed pulley assembly for use with a drive belt having a V-shaped cross-sectional configuration for transmitting driving force to the assembly, and a driven belt having a V-shaped cross-sectional configuration for transmitting driving force from the assembly. The pulley assembly includes an outer drive pulley half and an outer driven pulley half, supported for rotation with each other about an axis at locations spaced apart axially from each other. A center pulley is supported for rotation with the outer drive pulley half and the outer driven pulley half, about the axis, at a location axially intermediate the outer drive pulley half and the outer driven pulley half. The center pulley is movable axially in opposite directions between the outer drive pulley half and the outer driven pulley half. The center pulley comprises an inner drive pulley half and an inner driven pulley half fixed for rotation with each other. The inner drive pulley half has an outer surface presented at an angle to an inner surface of the outer drive pulley half to define between them a drive pulley groove. The drive belt is received in the drive pulley groove and is movable radially in the drive pulley groove between a radially innermost position and a radially outermost position. The inner driven pulley half has an outer surface presented at an angle to an inner surface of the outer driven pulley half to define between them a driven pulley groove. The driven belt is received in the driven pulley groove and is movable radially in the driven pulley groove between a radially innermost position and a radially outermost position.
At least one of the drive pulley groove and the driven pulley groove has an included angle between the facing surfaces which define the at least one groove. The included angle varies between the radially innermost position of the belt in the at least one groove and the radially outermost position of the belt in the at least one groove.